1. Field of the Invention
The present invention relates to a semiconductor device manufacturing method.
2. Description of the Related Art
Japanese Patent Laid-Open No. 2006-73611 describes a method of forming a charge accumulation layer of a photodiode in a position adjacent to a gate electrode by self alignment. In this method, a gate electrode is first formed by using a first mask pattern. Then, a second mask pattern is formed without removing the first mask pattern used in the formation of the gate electrode. Ion implantation is performed in a region defined by a common portion of the position of an opening of the first mask pattern and the position of an opening of the second mask pattern, thereby forming a charge accumulation layer of a photodiode. The charge accumulation layer of the photodiode is defined by the first and second mask patterns, and formed in a position adjacent to the gate electrode by self alignment.